Ambulance Emergency Response Optimization in Developing Countries

The lack of emergency medical transportation is viewed as the main barrier to the access of emergency medical care in low and middle-income countries (LMICs). In this paper, we present a robust optimization approach to optimize both the location and routing of emergency response vehicles, accounting for uncertainty in travel times and spatial demand characteristic of LMICs. We traveled to Dhaka, Bangladesh, the sixth largest and third most densely populated city in the world, to conduct field research resulting in the collection of two unique datasets that inform our approach. This data is leveraged to develop machine learning methodologies to estimate demand for emergency medical services in a LMIC setting and to predict the travel time between any two locations in the road network for different times of day and days of the week. We combine our robust optimization and machine learning frameworks with real data to provide an in-depth investigation into three policy-related questions. First, we demonstrate that outpost locations optimized for weekday rush hour lead to good performance for all times of day and days of the week. Second, we find that significant improvements in emergency response times can be achieved by re-locating a small number of outposts and that the performance of the current system could be replicated using only 30% of the resources. Lastly, we show that a fleet of small motorcycle-based ambulances has the potential to significantly outperform traditional ambulance vans. In particular, they are able to capture three times more demand while reducing the median response time by 42% due to increased routing flexibility offered by nimble vehicles on a larger road network. Our results provide practical insights for emergency response optimization that can be leveraged by hospital-based and private ambulance providers in Dhaka and other urban centers in LMICs

Cortisol and Testosterone in Hair as Biological Markers of Systolic Heart Failure

Congestive heart failure (CHF) is associated with increased stress and alterations in metabolism, favoring catabolism over anabolism. Hormonal profiles of patients with heart failure have been assessed using serum and saliva as matrices, which are only point measurements and do not provide long-term information. Scalp hair is a novel matrix that allows for measurement of hormones over a period of several months. We aimed to evaluate whether levels of cortisol and testosterone and their ratio (C/T) in hair correlate with severity of heart failure. We conducted a prospective study in ambulatory male patients with a left ventricular ejection fraction (LVEF) ≤40%. Hormone levels were measured using immunoassays in the proximal 2 cm of hair (representing approximately two months of systemic hormone exposure). Primary endpoints included the correlation of hair cortisol, testosterone, and C/T levels with the New York Heart Association (NYHA) class, LVEF, exercise capacity and NT-proBNP. The 44 CHF patients had a median hair level (range) of cortisol of 207 (117.7-1277.3) ng/g. Hair cortisol levels correlated positively with NYHA class (r=0.48, p=0.001) and negatively with treadmill stress test performance, (r=-0.37,

WiPrint: 3D Printing Your Wireless Coverage

Wireless signals are everywhere in residential, commercial and industrial environments. Directing wireless signals to conform to custom physical boundaries is of great importance in improving the performance, security and privacy of a wireless system. Unfortunately current solutions like directional antennas are bulky and expensive for ordinary users. We propose WiPrint, a novel approach to customizing wireless signal maps using 3D printed glossy reflectors. This solution is easily manufactured and adapts easily to different environments. The WiPrint system is highly flexible as it does not require adding additional APs or moving the AP to new locations. This is significant in the field of wireless networking as it provides consumers with an intuitive and novel solution to performance and security problems

Mixing the Old with the New: Chinese Traditional Medicine and The Regulation of Food and Drugs in the United States

The practice of traditional Chinese healing methods has secured a small but noticeable foothold in some sectors of American society. Whether this is simply yet another incarnation of the West's centuries-old romantic obsession with the exotic lure of the East, or a reserved but genuine concession to the virtues of a foreign medical discipline remains unclear. The purpose of this paper is to study the economic significance of Chinese traditional medicine and its implications for the American pharmaceutical industry and United States food and drug regulation

Investigation of Novel Thiol Click Reactions

The thio-Michael addition reaction is traditionally considered a base catalyzed reaction which involves high catalyst concentrations and long reaction times. This reaction utilizes potent, simple nucleophiles to catalyze the reaction, decreases the catalyst concentration and greatly increases the reaction times. The free radical mediated thiol-ene click reaction uses light or heat and an initiator to catalyze the rapid and quantitative addition of thiols to most electron rich enes without the formation of side products and in the absence of solvent. Recently, the thiol-ene click reaction has been exploited for these reasons in materials science and organic synthesis. The research herein describes the nucleophile catalyzed thio-Michael addition to electron poor enes as a integral reaction in the canon of thiol-ene click reactions. This dissertation includes chapters of the kinetics and spectroscopic evaluation of the nucleophile catalyzed thio- Michael addition reaction and resulting products; the use of nucleophile catalyzed thio- Michael addition for the rapid synthesis of star polymers; and the physical and mechanical properties of networks prepared with a combination of the photo-cured and nucleophile cured reactions of multi-acrylates with multi-functional thiols. This dissertation also discusses the less researched thiol-yne reaction, which provides the addition of two thiol groups to one alkyne group. Mechanistically, a thiyl radical adds to an alkyne group creating a very reactive thio vinyl radical, which, in turn, abstracts a hydrogen from another thiol creating a new thiyl radical. The resulting thio vinyl group, which shows higher reactivity than the initial alkyne, reacts rapidly with a second thiyl group. Additional chapters in this dissertation will discuss the formation of multi-functional materials (16 \u3e functionality \u3e 8) in a sequential nucleophile catalyzed thio-Michael addition followed by the thiol-yne reaction; the mechanical and physical properties of films prepared with multi-functional alkynes and multi-functional thiols; and the linear relationship of refractive index and sulfur content in polysulfide networks made possible by the thiol-yne reaction. The first fundamental study discusses a proposed anionic chain mechanism for the nucleophile catalyzed thio-Michael addition to electron poor alkenes. Traditional base catalyzed mechanisms show the deprotonation of the thiol by a weak base such as triethyl amine. Results show that nucleophilic amines, such as hexyl amine, with similar pKa values as the weak bases have faster rates of reaction, indicating that base strength alone is not responsible for the apparent increase in rates. Results demonstrate that the effect of nucleophilicity has a greater role than basicity (pKa) in the rates of reaction. An anionic chain mechanism is proposed involving the initiation of the thio-Michael reaction by an initial attack of a nucleophile onto an electron poor double bond creating a super-strong enolate anion which carries out the subsequent base catalyzed thio-Michael addition. The second study reports the facile formation of star polymers using the nucleophile catalyzed thio-Michael addition reaction of polymers prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization and a tri-acrylate monomer. The nucleophilic catalyst employed for the thio-Michael addition reaction has shown to have a dual purpose: to catalyze the Michael addition and to prevent the disulfide formation commonly seen in the reduction step of the RAFT end group. Acrylates are commonly used for the preparation of polymer networks due to their wide commercial availability, tunable mechanical properties, and sensitivity to photopolymerization. Photo-cured multi-acrylate systems produce films with inhomogeneous micro-structures leading to broad glass transition temperatures (Tg). Incorporation of thiols into these systems narrows the Tgs but quantitative addition (1 to 1) of thiol to acrylate does not occur due to the competitive acrylate homopolymerization. The nucleophile catalyzed thio-Michael addition reaction promotes the quantitative addition of thiols to acrylates resulting in very narrow Tgs. The third study discusses the use of sequential thio-Michael reaction followed by the photo-cured reaction. This process allows tunability of mechanical and physical properties of resulting films. In the fourth study, the nucleophile catalyzed thio-Michael addition reaction is used for preparation of multi-functional alkynes. Alkynes, like alkenes, react rapidly and quantitatively with thiols in a photocured system in a 1:2 ratio. A series of polyfunctional branched materials was prepared by clicking two thiol groups to one terminal alkyne proceeded quantitatively, in the absence of solvent, rapidly and with no evidence of side products. The fifth study demonstrates the preparation of a series of multi-functional alkyne monomers (f=4,6,8) that were subsequently photopolymerized with a series of multifunctional thiols (f=2,3,4). Mechanical and physical properties showed an increasing correlation between gel point and functionality. Additionally, this study demonstrated the utility of tailoring the Tg values by increasing the functionality of starting monomers. High sulfur content materials have shown to have high refractive index values. In the final study, networks were prepared from commercially available dialkyne and dithiols, consisting only of sulfur and hydrocarbon. Sulfur content in some films reached nearly 50% and, as a result, refractive index values were determined to be greater than 1.65. Data from this study shows a linear relationship between the weight% sulfur and the refractive index in sulfur containing crosslinked hydrocarbon networks

Underwater 3D positioning on smart devices

The emergence of water-proof mobile and wearable devices (e.g., Garmin Descent and Apple Watch Ultra) designed for underwater activities like professional scuba diving, opens up opportunities for underwater networking and localization capabilities on these devices. Here, we present the first underwater acoustic positioning system for smart devices. Unlike conventional systems that use floating buoys as anchors at known locations, we design a system where a dive leader can compute the relative positions of all other divers, without any external infrastructure. Our intuition is that in a well-connected network of devices, if we compute the pairwise distances, we can determine the shape of the network topology. By incorporating orientation information about a single diver who is in the visual range of the leader device, we can then estimate the positions of all the remaining divers, even if they are not within sight. We address various practical problems including detecting erroneous distance estimates, addressing rotational and flipping ambiguities as well as designing a distributed timestamp protocol that scales linearly with the number of devices. Our evaluations show that our distributed system running on underwater deployments of 4-5 commodity smart devices can perform pairwise ranging and localization with median errors of 0.5-0.9 m and 0.9-1.6

Towards a mechanistic understanding of fungal life history strategies: Dispersal and competition as critical components of saprotrophic fungal ecology

Saprotrophic fungi perform the vital role of cycling nutrients and carbon back into the environment through the decomposition of organic matter. But in a rapidly changing global environment, we do not fully understand how these environmental changes will affect the process of decomposition by saprotrophic fungi. To understand decomposition and carbon cycling at a global scale, we must first begin to identify the life history strategies that saprotrophic fungi employ. For saprotrophic fungi, resources are arrayed in patches in the environment, much like an archipelago of islands. On these resource islands, interspecific competition is intense and available resources are continually depleted as a consequence of fungal metabolism. Here, airborne dispersal is a key factor that allows fungi to avoid being restricted to an island experiencing total resource patch collapse and to persist within the environment. In this thesis, I take an experimental approach and explore how living in finite resource patches shapes allocation to dispersal in fungi, and how a resource patch can alter the course of interspecific competition. In Chapters 2 and 3, I tracked allocation to dispersal in saprotrophic fungi using Phacidium lacerum, a novel model species. In Chapter 2, I ran a Petri-dish experiment varying resource island size (Petri-dish size) and nutrient concentration to test how environmental quality influenced allocation to dispersal. In Chapter 3, I included both interspecific and intraspecific competitors to see how negative interactions changed patterns of allocation to dispersal. In Chapters 4 and 5, I focused on competition between saprotrophic fungi. In Chapter 4, I explored how the strength of competition varied across simple and complex substrates, and in Chapter 5, I tracked how wood decay was influenced by interspecific competition in a paired wood block experiment. Altogether, these studies highlight the importance of considering dispersal and competition in saprotrophic fungi, especially in the context of finite resource patches as islands

Liquidity and Asset Prices in Multiple Markets

Liquidity is generally viewed as a positive characteristic of a traded asset in positive net supply. Ceteris paribus, the higher liquidity of a given asset should be reflected in a higher price or a lower required return. This issue is of particular interest if the same asset is traded in multiple markets. In this setting, apart from the effect of liquidity on pricing in each market, there is the additional question of transmission of these liquidity effects across markets. This paper investigates the liquidity effect in asset pricing by studying the liquidity-premium relationship of an American Depositary Receipt (ADR) and its underlying share in the home market. Using the Amihud (2002) measure, the turnover ratio and trading infrequency as proxies for liquidity, we show that a higher ADR premium is associated with higher ADR liquidity, lower home share liquidity. We measure these effects, in terms of both the levels and changes, in both the premium and the liquidity variables. We find that the liquidity effects remain strong even after we control for firm size and a number of country characteristics, such as the expected change in the foreign exchange rate, the home country and the US stock market performance, as well as several variables measuring the openness and transparency of the home market

BlindSignedID: Mitigating Denial-of-Service Attacks on Digital Contact Tracing

Due to the recent outbreak of COVID-19, many governments suspended outdoor activities and imposed social distancing policies to prevent the transmission of SARS-CoV-2. These measures have had severe impact on the economy and peoples' daily lives. An alternative to widespread lockdowns is effective contact tracing during an outbreak's early stage. However, mathematical models suggest that epidemic control for SARS-CoV-2 transmission with manual contact tracing is implausible. To reduce the effort of contact tracing, many digital contact tracing projects (e.g., PEPP-PT, DP-3T, TCN, BlueTrace, Google/Apple Exposure Notification, and East/West Coast PACT) are being developed to supplement manual contact tracing. However, digital contact tracing has drawn scrutiny from privacy advocates, since governments or other parties may attempt to use contact tracing protocols for mass surveillance. As a result, many digital contact tracing projects build privacy-preserving mechanisms to limit the amount of privacy-sensitive information leaked by the protocol. In this paper, we examine how these architectures resist certain classes of attacks, specifically DoS attacks, and present BlindSignedIDs, a privacy-preserving digital contact tracing mechanism, which are verifiable ephemeral identifiers to limit the effectiveness of MAC-compliant DoS attacks. In our evaluations, we showed BlindSignedID can effectively deny bogus EphIDs, mitigating DoS attacks on the local storage beyond 90% of stored EphIDs. Our example DoS attacks showed that using 4 attackers can cause the gigabyte level DoS attacks within normal working hours and days.Comment: 10 pages, 6 figure

QCD_4 From a Five-Dimensional Point of View

We propose a 5-dimensional definition for the physical 4D-Yang-Mills theory. The fifth dimension corresponds to the Monte-Carlo time of numerical simulations of QCD_4. The 5-dimensional theory is a well-defined topological quantum field theory that can be renormalized at any given finite order of perturbation theory. The relation to non-perturbative physics is obtained by expressing the theory on a lattice, a la Wilson. The new fields that must be introduced in the context of a topological Yang-Mills theory have a simple lattice expression. We present a 5-dimensional critical limit for physical correlation functions and for dynamical auto-correlations, which allows new Monte-Carlo algorithm based on the time-step in lattice units given by \e = g_0^{-13/11} in pure gluodynamics. The gauge-fixing in five dimensions is such that no Gribov ambiguity occurs. The weight is strictly positive, because all ghost fields have parabolic propagators and yield trivial determinants. We indicate how our 5-dimensional description of the Yang-Mills theory may be extended to fermions.Comment: 45 page